水养护温度对活性粉末混凝土强度及水化硅酸钙结构的影响研究

Study on the Effect of Water Curing Temperature on the Strength and Calcium Silicate Hydrate Structure of Reactive Powder Concrete

活性粉末混凝土(RPC)水化产物的主体是水化硅酸钙(C-S-H),但其易受温度影响,具有复杂多变的特点。本文分析了水养护温度对RPC的28d强度的影响规律,并利用^(29)Si核磁共振(NMR)技术研究了水养护温度对RPC浆体水泥水化程度、C-S-H凝胶Si原子结构特征、硅氧链平均分子链长(MCL)及Al[4]/Si等微结构参数的影响规律,探明了活性粉末混凝土C-S-H硅氧四面体聚合机制。结果表明:随着水养护温度的升高,RPC的抗压、抗折强度逐渐增大,折压比先增大后降低,其水化程度、硅氧链平均分子链长、Al[4]/Si逐渐增大;当水养护温度≥50℃时,硅灰的火山灰反应加剧,进一步提高了RPC内部水泥水化程度、C-S-H平均分子链长及Al[4]/Si。

The main body of the hydration product of reactive powder concrete(RPC)is hydrated calcium silicate(C-S-H),but it is susceptible to temperature and has complex and variable characteristics.In this paper,it investigates the influence law of water curing temperature on the 28 d strength of RPC,and the influence law of water curing temperature on the microstructural parameters such as the degree of hydration of RPC slurry cement,the Si atomic structure characteristics of C-S-H gel,the average molecular chain length(MCL)of silica-oxygen chains,studies the Al[4]/Si by using 2'si NMR technology to investigate the mechanism of the polymerization of the C-S-H silica-oxygen tetrahedra of activated powder concrete.The results show that the RPC compressive and flexural strengths gradually increased with the increase of the water curing temperature,the flexural ratio firstly increased and then decreased,and the hydration degree of cement,the average molecular chain length(MCL)of siloxane chains,and Al[4]/Si gradually increased.When the water curing temperature is≥50 C,the volcanic ash reaction of silica fume intensifies,further increasing the degree of cement hydration inside RPC,the average molecular chain length of C-S-H,and Al[4]/Si.